Architecture and technical choices

This second iteration is about refactoring the code into independent and reusable verticles:

We will deploy 2 verticles to deal with HTTP requests, and 1 verticle for encapsulating persistence through the database. The resulting verticles will not have direct references to each other as they will only agree on destination names in the event bus as well as message formats. This provides a simple yet effective decoupling.

The messages sent on the event bus will be encoded in JSON. While Vert.x supports flexible serialization schemes on the event bus for demanding or highly-specific contexts, it is generally a wise choice to go with JSON data. Another advantage of using JSON is that it is a language-agnostic text format. As Vert.x is polyglot, JSON is ideal should verticles written in different languages need to communicate via message passing.